The M3 has been an overall sales failure since 2008, no matter how it is spun. It used to be that the E46 M3 sales (Coupe and Convertible) in the USA alone was around 8000 a year. Now it barely exceeds that worldwide.

That's messed up.

With that said, that sales failure is not because of any inherent E9x M3 deficiency, it is just that between the economy, the fuel economy concerns/prices and the jump into the $70,000+ bracket -in the USA- it simply tanked, IMO.

I don't think yours is an apples to apples comparison. I see the logic in comparing e46 coupe and convertible sales figures against e92 coupe and convertibles sales figures. But the more appropriate comparison is sales of M's across the entire 3 series range of that generation. Why? because in this generation sales of the coupe and convertible become cannibalized as a result of the fact that the consumer has one additional choice - the sedan. That option didn't exist for purchasers of the e46, so a lot of people were just forced to grin and bear it. People who would have maybe bought a sedan then, bought a coupe instead because it was their only option.

I'm not sure what the worldwide sales figures look like for the e46 generation M3, but as for this generation the figure is not 8k, but rather about 10k+ (5729 coupe, 2544, convertible, 1843 sedan).